Since it was first announced in August 2012, Microsoft has made investments in four small start up companies via its Bing Fund. Today, it announced its fifth such venture and this time the money is going to help a company that has launched a mobile app for iOS and Android.

Sonar is interesting to Microsoft in a number of ways, both as a product and a business. Extracting knowledge from social signals. Fostering informed serendipity. Real-time geo data. A quality team with a mature service. The possibilities with the caliber of company like Sonar are numerous, and exciting.

This is the first such investment from the Bing Fund that's being used to help a company that has a product that can only be used by Microsoft's competitors in the smartphone market. The blog gives no indication on when, or even if, Sonar might make a version of its app for Microsoft's operating systems. As with the previous Bing Fund announcements, the specific terms of the investment by Microsoft to Sonar were not revealed.